A refrigeration cycle apparatus including a constant-speed compressor performs the start-stop operation (operation of repeating start and stop) when a thermal load is low. When the compressor is stopped, high-temperature and high-pressure liquid refrigerant stored in a condenser flows into an evaporator on the low-temperature and low-pressure side. As a result, the evaporator is heated by and filled with this liquid refrigerant.
At the restart of the refrigeration cycle apparatus, it is necessary to move the liquid refrigerant stored on the evaporator side to the condenser side again by the work of the compressor. Therefore, there are problems of a delay in cooling and heating restart time and an increase in consumed power in the compressor.
Also in the case of a refrigeration cycle apparatus including an inverter compressor whose driving frequency can be controlled, when the frequency of the compressor reaches the lowest frequency for control, the inverter compressor cannot operate with the capacity equal to or lower than the lowest frequency. Therefore, the refrigeration cycle apparatus including the inverter compressor also performs the start-stop operation. Accordingly, similarly to the refrigeration cycle apparatus including the constant-speed compressor, there are problems of a delay in cooling and heating restart time and an increase in consumed power in the compressor.
PTD 1 (Japanese Patent Publication No. 63-46350), for example, discloses an air conditioner in which a state of refrigerant separated into the high-pressure side and the low-pressure side is kept during stop of a compressor, and thus, an energy loss at the restart of the compressor can be reduced and the state can be moved to a steady operation state in a short time. In this air conditioner, an expansion valve is closed during stop of the compressor, and thus, the high-temperature and high-pressure liquid refrigerant is enclosed in a condenser between a check valve placed in a compressor discharge pipe and the closed expansion valve.